1. Technical Field
The present invention relates to a serial communication system between a master and a slave, and more particularly relates to a serial communication system which uses an I2C bus as a serial bus.
2. Related Art
“I2C bus” is an abbreviation for Inter-IC bus, also called an IIC bus or an I2C bus, and refers to a serial bus in which two signal lines, carrying a serial clock and serial data, connect a plurality of devices, to perform serial data transfer between a master (a managing device) and a slave (a managed device).
Technology employing such I2C buses for communication between devices has for example been disclosed in JP-A-2000-242573, JP-A-2005-128747, JP-A-7-200320, JP-A-8-23582, and JP-A-11-53307.
In a communication method using an I2C bus as described above, when starting communication the master must first acquire the right-to-use for the bus. Then, the master issues start conditions, and then issues the slave address to specify the slave.
In such master-slave global serial communication, there have been the problem that a master cannot simultaneously access a plurality of buses, the problem that a master and slave can always perform only one-to-one communication, and the problem that a master cannot simultaneously access a plurality of slaves.